1. Field Of The Invention
This invention relates to improved polyethylene terephthalate compositions useful for molding resins and classified as engineering plastics.
2. Description Of The Prior Art
Japanese patent applications Nos. 71-32867 entitled A Method Of Injection Molding Polyethylene Terephthalate and 73-31247 entitled Polyethylene Terephthalate Blends With Improved Elongation And Impact Strength and General Electric U.S. Pat. No. 3,953,994 entitled Polyester Alloys And Molding Compositions Containing The Same show PET compositions containing minor amounts of polybutylene terephthalate (PBT).
Avery et al. U.S. Pat. No. 4,212,791 entitled Polyalkylene Terephthalate Molding Compositions Containing Oligomeric Polyesters And Segmented Copolyester-Polyether Elastomers teaches away from the replacement of the segmented elastomers with PBT because of detriment to surface appearance.
U.K. Pat. Nos. 2015014A and 2015013A to DuPont show alkali metal salt of organic acids and low molecular weight organic esters of aromatic carboxylic acid to improve surface appearance of PET.
Bayer U.S. Pat. No. 4,223,113 teaches oligomeric polyester plasticizers in polyalkylene terephthalate compositions for improvement in crystallization behavior.